UNIVERSITY of MOLISE Department of Agricultural, Environmental and Food Sciences
Total Page：16
File Type：pdf, Size：1020Kb
UNIVERSITY OF MOLISE Department of Agricultural, Environmental and Food Sciences INTERNATIONAL Ph.D. in “WELFARE, BIOTECHNOLOGY AND QUALITY OF ANIMAL PRODUCTION” (XXVI CYCLE) Related disciplinary scientific section: 07/G1 (Scienze e Tecnologie Animali) General Coordinator: Prof. Giuseppe Maiorano Doctorate Thesis Title: Influence of multiple injections of vitamin E on quality traits and oxidative stability of lamb meat Ph.D. Candidate: Dr. Domenico Di Memmo 143440 Supervisors: Prof. Mario Gambacorta Prof. Giuseppe Maiorano ACADEMIC YEAR 2013/2014 PhD thesis Domenico Di Memmo To Amy PhD thesis Domenico Di Memmo Acknowledgments I would like to thank my co-supervisor, professor Giuseppe Maiorano, and my supervisor, professor Mario Gambacorta, for their invaluable inputs towards the completion of this work. Working with You was a big privilege and an unique opportunity to improve my knowledge. I would also like to thank the University of Molise. Secondly, my heartfelt gratitude goes to all the people that I met during the International PhD study, and to all my collegues in “Welfare, Biotechnology and Quality of Animal Production”, in particular to Ms. Abiuso Cinzia, Ms. Cianciullo Daniela, Mr. Di Iorio Michele, Mr. Gentile Andrea, Ms. Mucci Rossella, Ms. Nardoia Maria, Ms. Rocco Martina, Ms. Tavaniello Siria, Ms. Wilkanowska Ania, Mr Vizzarri Francesco. Thank’s for their overwhelming support. I extend my thanks also to my Polish tutor professor Marek Bednarczyk and to all my Polish colleagues. A big thank you goes to my family, to my friends who have encouraged me through the course of the work. To the farmers that I met during this period I extend my sincere gratitude for your invaluable input without which this work would not have been completed. Thank you so much and keep up the good work. To all those whose I have not mentioned the name and who, in one way or another, contributed to the success of this work, I want to give my sincere thanks. PhD thesis Domenico Di Memmo Abstract Transporting animals to the slaughterhouse can increase the susceptibility of meat quality and, therefore, influence the value of pH, TBARS and the oxidation of fatty acids and pigments. Lipid oxidation cause negative changes on structure and nutrition value such as meat flavour, odour and colour: it is well know that colour is the characteristic that more affects the decision of the consumer to purchase. For this reason a supply of antioxidants is recommended to preserve the health of animals and the oxidative stability of their products. One of the most widely used antioxidants in animal diet is vitamin E. It is a lipid soluble and chain breaking antioxidant that protect cellular membranes against oxidative damages. The most active and natural form of vitamin E is -tocopherol. It is now accepted that dietary supplementation with -tocopheryl acetate controls lipid oxidation and colour deterioration in red meat like lambs and beef. In literature has been reported that intramuscular injections of tocopherols had a quite similar effect to the supplementation of vitamin E in diet. However, controversial information regarding the productive performances are also showed in some works on lambs. No information exists in literature on performance and meat quality traits of Laticauda lambs injected with Vitamin E. Laticauda is an autochthonous breed of Campania Region in Italy, that is usually reared by small family farms under semi- extensive systems. It derives from crossbreeding local sheep from the Appennines breed with fat-tailed North African sheep, imported in the XVIII century. Laticauda breed has a prevailing attitude toward meat production, associated to a good prolificacy. In the light of the above mentioned, the aim of the study was to determine the effect of DL-α-tocopheryl acetate injections on carcass and meat quality traits in growing lambs. Twenty-four 15-d-old Laticauda male lambs were randomly allotted to two groups: control (C, n =12) or vitamin E-treated (V, n=12). From the beginning of the study (15 days of age) until day 57 of age, each lamb of the V group received, weekely, i.m. injections of DL-α-tocopheryl acetate (right gluteus) in aqueous solution (Vitalene® E, Fatro, Bologna) for seven weeks for a total dose of 1,500 IU. The first injection consisted of 150 UI (3ml of Vitalene), while the other 6 injections consisted of 225 IU (4.5 ml of Vitalene). C group lambs received injections of physiological saline. I PhD thesis Domenico Di Memmo The animals were slaughtered at 64d of age. Hot and cold carcass weights were recorded and dressing percentages were calculated after dressing and chilling (2–4 °C for 24 h). After chilling, pH, colour, area, water holding capacity of M. longissimus dorsi (LD) were measured and shrink losses were calculated. After the refrigeration period (24 h at 2-4 °C), from the left side of the carcass the pelvic limb, loin and shoulder were removed and theirs percentage was calculated based on cold carcass weight. Vastus lateralis (VL) and longissimus dorsi (LD) muscles were removed for laboratory analyses (LD: fatty acids, cholesterol, intramuscular collagen, crosslinks; LD and VL: α-tocopherol content). For the same muscles TBARS (µg MDA/g tissue) at 24, 48, 96 and 192 h post mortem were measured during aerobic display at 5°C. Sensory analysis was performed on the pelvic limb from the left side of each lamb carcass, having two panels: one for the students, and the other one for customary consumers of lamb meat. Each panellist was required to evaluate the sample considering the intrinsic characteristics of the meat – tenderness, juiciness, flavour and overall acceptability (general pleasantness) – according to an unstructured line scale ranging from 1 (―very unpleasant‖) to 9 (―very pleasant‖). Vitamin E administration did not influence significantly live weight, carcass traits, except the incidence of pelvic limb, significantly higher in V group lambs; LD quality traits did not differ between the experimental groups, except for the red colour value (a*) that was higher (P<0.05) in lambs of vitamin E group. Treatment with vitamin E did not significantly affect the total SFA content and the proportion of single SFA, except for a slightly higher (P < 0.08) content of lauric acid (C 12:0) and lower (P < 0.01) content of eptadecanoic acid (C 17:0) in V group. Likewise, vitamin E treatment did not affect the total MUFA amount, except for a lower (P < 0.01) content of C 17:1 and higher C 18:1 n-9 trans (P < 0.05) and C 22:1 (P < 0.01) in V group. The oleic acid (C18:1 n-9 cis) was the most concentrated fatty acids (40-41%), followed by palmitic (20-21%) and stearic acids (14-15%). Vitamin E treatment positively affected the total PUFA content being higher (P < 0.01) in the V group compared with the control group. The vitamin E treated group had a significant higher amount of n-3 long chain PUFA: eicosapentaenoic fatty acid (EPA, C20:5n-3, P < 0.05), docosapentaenoic fatty acid (DPA, C22:5n-3, P < 0.01) and docosahexaenoic fatty acid (DHA, C22:6n-3, P < 0.06). Also vitamin E group had higher (P < 0.01) content of C 22:2. In light of this, the total n-3 FA content was higher (P < 0.01) in II PhD thesis Domenico Di Memmo treated lambs compared with the control group; while, no significant differences were found for the total n-6 FA amount. The n-6/n-3 ratio was lower in treated lambs (P < 0.01). The P/S ratio was higher (P < 0.01) in treated lambs. Trombogenic index was affected by the treatment being lower (P < 0.01) in vitamin E group. Cholesterol content was found to be not significant (P > 0.05) between groups (78.78 versus 79.01 mg/100g in C and V, respectively). Collagen characteristics were not significantly (P > 0.05) influenced by the treatment. The treatment with vitamin E markedly increase (P < 0.001) the content of DL- α-tocopherol in both muscles (longissimus dorsi: 0.92 versus 6.41 µg/g in C and V, respectively; vastus lateralis: 0.99 versus 7.31 µg/g in C and V, respectively) and increases the meat shelf life. This was evident since muscle tissue lipoperoxidation levels (TBARS) were significantly lower (P<0.01) in vitamin E injected lamb meat (longissimus dorsi and vastus lateralis muscles) at 24, 48, 96 and 192 h post mortem, during all the aerobic display at 5°C. The panel test showed that both the adult and the student judges, enjoyed both types of meat, giving a slightly higher point for the lamb that was injected with vitamin E if compared to the other type of meat (7.24 versus 6.97 respectively; P > 0.05). Therefore, both expressed a greater pleasure with the meat produced from lamb injected with vitamin E if compared to the meat of control group, as regard the descriptor of tenderness (6.66 versus 5.70, respectively; P< 0.05) and juiciness (6.39 versus 5.00; P < 0.05). At the light of the above, the conclusion of this study is that the intramuscular administration of vitamin E can be recommended to obtain meat with a higher nutritional and commercial value. III PhD thesis Domenico Di Memmo Riassunto Il trasporto degli animali prima della macellazione, ed altri fattori di stress, possono influenzare le caratteristiche chimico-fisiche delle carni, e di conseguenza i valori di pH, TBARS e l‘ossidazione di acidi grassi e pigmenti. Questo processo causa peggioramenti qualitativi sia dal punto di vista nutrizionale che commerciale, soprattutto per quanto concerne l‘aroma e il colore delle carni, fattori che influenzano enormemente le scelte di acquisto del consumatore.